Pyrometer tube



80 other end connects with Patented July 26, 1932 UNITED STATES PATENTOFFICE JOSEPH A. JEFFERY AND FRANK HI. RIDDLE, OF DETROIT, MICHIGAN,ASSIGNORS 'IO CHAMIPION PORCELAIN COMPANY, OF DETROIT, MICHIGAN, ACORPORATION OF MIOHIGAN Application filed Mayli', 1926. Serial No,109,473.

ure temperatures of furnaces, and where they a P are used in otherpositions in which there are likely to be gasesor vapors deleterious tothermo-couples, are usually supported in gas tight tubes. The usualmaterial for such tubes is porcelain.

Usually, one end of apyrometer tube projects into the furnace or otherlocation, the temperature of which is to be tested, and its a headhaving binding posts and leads for making electrical connections betweenthe thermocouple and an M indicating device.

It has been customary to remove a thermocouple from the place in whichit is being used, and take it to the laboratory for calibration. Thismethod has several disadvantages, particularly if the set up is in anextremely warm or rather inaccessible position. If the thermo-couple isremoved from the tube, there is considerable difficulty, and apossibility of breaking the platinum wires, also in reconnecting thereis a possibility of not getting the set up quite the same as before, orthe same as the set up in laboratory during testing. Where the tube istaken out with the thermocouple, there is considerable danger ofbreaking the tube during handling. alsothe possibility. of letting dirtthrough the port into the furnace, protection tube, if there be one.Putting the cool tube back into the hot furnace is likely to break itand contaminate the couple.

The removal and reinstallation of the set up must be done by a skilledoperator, and the operation is very unpleasant, and the incidentbreathing of partially combusted gases quite often? results seriously.The time consumed in removing the couple, calibrating or testing, andreplacing is considor into the outer erable, and during this time theequipment must be run without the aid of a pyrometer or else asubstitute couple must be employed, with the resultant necessity ofmaking two removals and reinstallations, instead of one.

Sometimes a furnace has been provided with an additional opening inwhich the tube of a standardized pyrometer could be placed for testingpurposes; but this requires a special construction of the furnace, whichis expensive and of no utility except when tests are needed, and exposesthe tube of the standard pyrometer to danger of breakage duringhandling. The heat conditions in a furnace are seldom uniform, and thepyrometer tubes are frequently protected by edcas ng blocks, which mayvary in conductivlty, so that it is impossible to eliminate the doubt asto whether any discrepancy in the reading of the standard instrument andthe regular equipment is due to a difference in the pyrometer or to adifference in the heat conditions to which their thermocouples aresubjected.

We avoid the above and other difiiculties by our invention, which willbe described in connection with the accompanying drawing, forming a partof this specification.

In the drawing, Figure 1 is a section of a portion of a furnace wall,showing a pyrometer tube and connections which may be used in carryingout our invention; Fig. 2 is an enlarged section on the line 2-2, Fig.1; Fig. 3 is a plan view of the end closure with its lid open; Fig. 45is a section on the line 4.4, Fig. 2; Figs. 5 and 6 are sections similarto Fig. 4 of alternative forms of tubes.

In the form of device shown, a tube 10 is mounted in a bushing 11adapted to be inother suitable means, and holds both bushing and tube inproper position.

Enclosure 12 is formed by base plate 17 having an upstanding flange 20,and a lid 21 having a flange 22 adapted to abut flange 20. The lid hasoutstanding lugs 24 which are pivoted at 25 to an upstanding lug 26 onflange 20. A clamping bolt 27 is pivoted to lugs 28 on the base plateand has a clamping nut 29 adapted to bear on lugs 30 on the lid ailid sohold the lid clamped against the base p ate.

A thermo-couple 31 is mounted within the tube, and is connected by leads32 to binding posts 33 and 33 suitably mounted on plate 18. From thesebinding posts leads 34 pass out throughan opening 35 in flange 20, andthrough conduit 36 to an electrical indicator, not shown, adapted toindicate the temperature to which the thermo-couple is subjected. I

It is desirable to surround, 0r substantially surround, thethermo-couple with a tube which is of substantially even thickness andheat transmitting power, and which is approximately equi-distant at allpoints from the thermocouple, so that heat from 'various directions istransmitted to the thermo-couple in a substantially uniform manner.

A uniform cylindrical tube answers these requirements, and is acustomary form of tube. Our preferred form of tube is shown in Figs. 2and 4. i The cross section ofthis tube is shaped like a figure 8. It isformed of two substantially cylindrical members 37 and 38 arranged soclosely side by side that they overlap, and as a result there is a smallslit 39 connecting the two channels 40 and 41 of the tube. The end ofthe tube is formed of two substantially hemispherical portions 42 and43. Such a tube heats a thermocouple in either of its channelssubstantially the same as a cylindrical tube, and both channels areheated substantially the same. The channels act as guides, so that athermocouple may be inserted in or withdrawn from one channel withoutdanger of injurious contact with a thermo-couple in theother channel.

When the thermo-couple 31 in channel 40 of our pyrometer is to betested, the thermocouple of a. standard pyrometer is inserted in channel41. It will be seen that the regular equipment doesnot need to bedisturbed in order to test it, that no additional tube is needed for thestandard pyrometer, and that the thermo-couple will be affected insubstabntially the same way by heat around the tu e.

In Fig. 5 a tube is shown differing from that shown in Figs. 2 and 4 byhaving the cylindrical. walls of portions 137 and 138 completed, so thatthere is a dividing wall 391 between the two channels 140 and 141. Thishas the by a wall equi distant therefrom at all points,

but does not allow the interchange of gases between the channels.

In Fig. 6 there is shown a cross section of a tube having twosemi-cylindrical portions 237, 238 connected by straight side walls 44and 45. This tube has the wall equi-distantfrom the thermo-couplethrough only 180, and does not furnish a guiding groove to aid inpositioning a thermo-couple, but has the advantage of free interchangeof gases between the portions surrounding two thermo-couples locatedalong the axes of the respective portions 237 and 238.

Although the lower ends of the tubes shown in Figs. 5 and 6 are notshown, it will be readily understood that the lower end of the tubeshown in Fig. 5 is formed of two semi-spheri- .any necessity forchanging the structure of the furnace or other inclosure with which thepyrometer is associated, and allows the testing of the thermo-couple orentire pyrometer in such an accurate and expeditious manner that itrenders practicable the frequent testing which is necessary to avoidtrouble from false heat indications. 1

Various changes may be made in the form of device shown, and while weprefer, and claim as especially useful, a tube having a shape in crosssection substantially like a figure 8, the invention is not confined tothe exact shape of the tube except where this is made a part of theappended claims. Some of the benefits of our invention may be attainedwith tubes of shapes other than those shown, and various other changesmay be made, in the device illustrated, without departing from the scopeof the appended claims. y

In the appended claims the expression portable pyrometer tube isintended to cover a tube capable of being inserted in place of the usualpyrometer tube, and to distinguish from a block which forms a part of afurnace wall.

What we claim is:

l. A pyrometer tube having walls of substantially equal thicknessthroughout, and

having therein two substantially cylindrical parallel channelscommunicating with each' an interior hollow space for a singlethermocouple, and having an interior hollow space, the shape of saidtube and space providing permanent two similarly located axeslongitudinally of the space, and a casing within which the head of thetube is removably mounted, said casing being provided with means formounting a thermo-couple along each of said axes.

3. In combination, a portable pyrometer tube having a hollow spaceprovlding two parallel longitudinal axes, said tube being closed at oneend and open at the other and having a flange about its open end, aplate within which said flange is removably seated and means providing ahousing over the open end of the tube and means within said housing formounting a thermo-couple along each of the axes of said tube.

4. An integral portable pyrometer tube oblong in cross section andhaving two parallel axes, one adjacent each end of said oblong section,the side portions formin the ends of said oblong sections beingequl-distant from the respective axes, and the walls of the tube beingof substantially uniform thickness and being equally and similarlyspaced from the respective axes, and one end of said tube being closedby walls similarly located with respect to the two axes.

5. An integral portable pyrometer tube oblong in cross \section andhaving a single longitudinal channel therein closed at one end and openat the other end, the walls of the tube being of substantially uniformthickness throughout except for a flange around the open end, and thewalls of the tube and the opening therein being formed with twolongitudinal-parallel axes with the walls on opposite sides of said axesconstituting semicylindrical portions about said axes.

In testimony whereof, we have hereunto signed our names to thisspecification.

JOSEPH A. JE-FFERY. FRANK H. RIDDLE.

